Authors

Bruce G. Pohlot

Document Type

Internship Report

Publication Date

Spring 2011

Abstract

The Northwest Atlantic’s pelagic longline fishing fleet has been required to use circle hooks since 2004, following research indicating the use of these hooks to reduce bycatch release mortality of elasmobranchs, marine mammals, sea turtles, and juvenile target species. Although much research has been invested in examining the effects of circle hook use on catch rates and factors affecting release mortality, no studies have examined the effect on the quality of retained target species, such as swordfish and bigeye tuna . This study evaluates the veracity of the suggestion made by several researchers that improved quality fish product will result from the increased jaw hooking and live boarding of fish associated with the use of circle hooks (Watson et al. 2005; Erstetter and Graves 2002; Serafy et al. in review). An analysis of swordfish and bigeye tuna quality grades was performed using observer recorded information regarding individual fish characteristics, such as if the fish was alive or dead, how the fish was hooked, and what type of hook and bait combination was used . In 5 circle hook to J- hook comparisons, 4 demonstrated that circle hooks obtained significantly higher quality grades in 2002 and 2003. In all comparisons, circle hooks either improved, or were equivalent in, resulting fish quality. The contentions made by Watson et al. (2005) and Kerstetter and Graves (2002) were confirmed with live boarded swordfish displaying significantly higher grades in 2002 and 2003, while bigeye tuna were graded significantly higher only in 2002. Mouth hooked swordfish and bigeye tuna obtained significantly higher quality grades in 2002. These results highlight the potential benefit of circle hook use to the resulting quality of fish product brought to market by the fishermen . It is likely that high quality fish will obtain a higher price, possibly improving fishermen’s revenue and supporting expanded circle hook use beyond US regulatory boundaries.

Comments

Department: MBF

MPS Track: Fisheries Science

Location: National Oceanographic and Atmospheric Administration, National Marine Fisheries Service / SEFSC

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